Present light emitting diode and/or photovoltaic devices are typically formed vertically on substrates, i.e. the layers (cathode, anode, semiconductor) are fabricated on top of one another so as to be stacked normal to the substrate. This is done because it is easier to fabricate a large PN junction region in this manner.
However, in this configuration, the layers of the semiconductor material are typically relatively thick, typically >>100 nm, to substantially avoid short circuits in the electrooptical device. This is because of the potential for voids in overly thin semiconductor layers that may allow an electrode formed on top of the semiconductor layer(s) to contact an electrode formed below the semiconductor layer(s). Due to these thick semiconductor layers, the efficiency of typical electrooptical devices is decreased due to light blocked by the electrode. Also, in photovoltaic (PV) devices, the excess thickness of the semiconductor may lead to significant loss due to charge recombination before the charge can be separated by the junction; and, in electroluminescent (EL) devices, photons may be reabsorbed before they traverse the thick semiconductor material layer(s). In addition, if the stacked structure includes a charge generation layer (electrode), this layer may cause processing difficulties and/or may block incoming or outgoing light.
Exemplary embodiments of the present invention overcome these and other issues associated with the fabrication of electrooptical devices.